Conan, Belit, and the Black Corsairs are finally back aboard the Tigress, and out to Sea. While sailing the open waters they soon come across a strange sight indeed - a beautiful woman.

She seems to hover above the water mysteriously, as if standing on some giant lily pad. While Belit and Conan believe she is some form of Sea-Witch, the old and wise N'yaga begs she be brought aboard. Strangely, as soon as she is, N'yaga is stricken with some mysterious ailment, while all the Corsairs seem ensorcelled by the woman.

Meanwhile, the crew of the Tigress spot a Stygian Merchant Vessel, and do what they do best - loot and plunder the ship and send the vessel and its crew to the bottom of the Sea.

Strange occurrences start happening around the mysterious woman, even the disappearance and death of some of the crew members. Can Conan resist the silent song of the Sea-Witch, before it's too late?